<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        body{
            height: 3000px;
        }
        .kkk{
            height: 200px;
            background-color: blue;
        }
        .nav{
            height: 80px;
            width: 500px;
            background-color: pink;
            margin: 0 auto;
            top: 100px;
            position: sticky;
        }
    </style>
</head>
<body>
    <div class="kkk"></div>
    <div class="nav">我是导航栏</div>
</body>
</html>